Apparatus for controlling engine intake pressure with variable-speed blower and engine throttle



0011A ET AL Aug. 28, 1951 .J'. APPARATUS FOR CONTROLLING-ENGINE. INTAKE PRESSURE WITH l0 Sheets-Sheet l R F Q a a Q a m Q s a o 3r R a? K. D H A, a an 4 U 0 n wa A w: N \N MN UJOWAIJUM III/W W] Aug. 28, 1951 J. DOLZA ETAL 2,565,482 APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE WITH VARIABLE SPEED BLOWER AND ENGINE THROTTLE Filed Sept. 7, 1944 10 Sheets-Sheet J. DOLZA ETAL 2,565,482 FOR CONTROLLING ENGINE INTAKE PRESSURE WITH Aug. 28, 1951 APPARATUS VAR Filed Sept. 7, 1944 IABLE SPEED BLOWER AND ENGINE THROTTLE v l0 Shee+s-Sheet 5 Aug. 28, 1951 DOLZA EI'AL 2,565,482

APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE WITH VARIABLE SPEED BLOWER AND ENGINE THROTTLE Flled Sept 7 1944 10 Sheets-Sheet 4 chi m ATTORNEW J. DOLZA ET AL 2,565,482 APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE WITH VARIABLE SPEED BLOWER AND ENGINE THROTTLE l0 Sheets-Sheet 5 8 w 2 S w w n A F uQ sQ E 1951 J. DOLZA ET AL 2,565,482

APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE WITH VARIABLE SPEED BLOWER AND ENGINE THROTTLE Filed Sept. 7, 1944 Aug. 28,

10 Sheets-Sheet 6 8, 1951 J. DOLZA ETAL 2,565,482

APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE WITH VARIABLE SPEED BLOWER AND ENGINE THROTTLE Filed Sept. 7, 1944 10 Sheets-Sheet 7 s N u 2 i. v a: 3' El A Q A R E Us 5 k T3 R "5| 3 8 8 Y Q 8 3 Q Q INVENT? 4/ a :3 {3 ,dflj/n M01177 ATTO R N EYp,

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APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE wrm VARIABLE SPEED BLOWER AND ENGINE THROTTLE Filed Sept. 7, 1944 10 Sheets-Sheet 9 Iowa [Jam TURBO I SPEED Jun JIM

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APPARATUS FOR CONTROLLING ENGINE INTAKE PRESSURE wrm VARIABLE spam) BLOWER AND ENGINE mom 1o sheets-sheet 10 Filed Sept- 7, 1944 Mk Q KQ WEQRMEQM m6 htvib Patented Aug. 28, 1951 APPARATUS FOR CONTROLLING ENGINE IN- TAKE PRESSURE WITH VARIABLE-SPEED BLOWER AND ENGINE THROTTLE John Dolza, Arthur W. Gaubatz, Peter W. Perish,

Donald P. Croissant, and Frank W. Ker-foot, Indianapolis, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September '1, 1944, Serial No. 553,050

This invention relates to a supercharged airplane engine, the intake pressure of which is boosted by an engine driven supercharger and an auxiliary supercharger operated by an exhaust as turbine.

It is an object of the invention to provide for the automatic control of the intake pressure through the use of a throttle valve regulator and a turbine speed controller coordinated therewith. The throttle valve regulator is manually conditioned by the pilots throttle control lever to select engine speeds and engine intake pressures to be 40 Claims. (Cl. 60-13) maintained according to a predetermined schedule. The throttle valve regulator has means responsive to intake pressure for controlling through a servomotor the position of the throttle valve in order to correct for divergencies from the selected pressure as the altitude changes. The turbine speed controller has a servomotor which controls the turbine waste gate and which is under control by the pilot's throttle lever, by an altitude pressure responsive device and by pressure at the outlet of the auxiliary supercharger. All of these controls are so coordinated that the auxiliary supercharger outlet pressure will conform to a predetermined relation to engine manifold pressure and engine speed in order to obtain the required engine power output at high altitude.

More particularly, the objects include provisions for stability of the control of the exhaust turbine and for operation of the control in a manner such that surge at the auxiliary supercharger is prevented, and such that the maximum safe turbo-speed is not exceeded, even when the duct between the auxiliary supercharger and the carburetor fails or is punctured in combat.

A further object is to obtain under certain special conditions intake pressures which are in excess of the maximum pressure which ordinarily can be used without engine detonation. Examples of the special conditions under which the pressure may be safely raised to a very high value are the use of alcohol-water-injection, the use oi a liquid cooled intercooler or aftercooler or both, and the use of a special fuel which can be burned without detonation at high intake pressures. The present invention includes means rendered operative automatically in response to the cessation of such conditions for returning the maximum pressure to a lower value safe for engine operation without these conditions being present.

Further objects and advantages of the'present invention will be apparent from the following de scription, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a diagram of the present invention.

Fig. 2 is a longitudinal sectional view of the throttle valve regulator shown in Fig. 1.

Fig. 3 is a sectional view on line 3-4 of Fig. 2.

Fig. 4 is an end view of the waste gate controller looking in the direction of arrow 4, Fig. 1.

Fig. 5 is an end view looking in the direction of the arrow 5 of Fig. 1.

Figs. 6 and 7 are sectional views taken respectively on lines 6-6 and of Fig. 5.

Fig. 8 is a side view of the waste gate controller looking in the direction of arrow 8 of Fig. 4.

Fig. 8A is a sectional view showing the attachment of hub to of lever I to shaft I".

Fig. 9 is a sectional view on line 88 of Fig. 8.

Fig. 10 is a fragmentary view showing certain relative positions of cam H0, lever H2 and lever I.

Fig. 11 is a sectional view on line ll-ll of Fig. 4.

Figs. 12, 13, 14, 15, 15A, 150, 16 and 17 are sectional views taken respectively on the lines l2l2. l2ll, ll-il, lB-li, IDA-45A, IBC-IIC. [6-46 and l|l| of Fig. 11.

Fig. 153 is a sectional view on line IBB-IIB of Fig. 15.

Figs. 18 through 24 are charts showing the operation of the present invention.

Referring to Fig. 1, air for the fuel mixture enters through an air-scoop it to an auxiliary supercharger 20 which is operated by an exhaust gas turbine 2| fed by a distributing manifold 22 connected with an engine exhaust pipe 22. The distributing manifold 22 has an outlet 24 controlled by a waste gate 25 mounted on a shaft 26. A pipe 21 conducts compressed air from the auxiliary supercharger 20 to an intercooler 22, the outlet of which is connected by pipe 29 with a carburetor 30 controlled by throttle valve ll, mounted on a shaft 32. The outlet of carburetor 20 is connected by pipe 33 with an engine driven supercharger 34 connected by manifold 25 with the intake ports of the engine.

Throttle valve 3| is manually controlled by the pilot's throttle lever 40 pivoted at ll and connected by link 42 with a lever 43 which operates a shaft 44 indicated by dot-dash lines. Shaft 44, which is the main control lever of a throttle valve regulator 50, is connected with an arm 4: providing a pivotal support 48 for the fulcrum of a floating or differential bell-crank lever having; arms 41 and 48. Ann 41 is connected by a link 49 with a lever 32a connected with throttle shaft 32. By this mechanism the throttle valve II is manually controlled by the pilots lever 40. The throttle valve 3i is automatically controlled by the throttle controller 50 through an hydraulic servomotor comprising a cylinder 5| enclosing a piston 52. connected by rod 53, pin 54, link and pin 55 with the differential lever arm 88. The servomotor is controlled by a valve 51 sliding in a valve guide 58. Valve 51 controls the distribution to either end of cylinder 5i of pressure fluid, which enters through an intake port 58, either to the right side of the piston 52 through a port 68 or to the left side of the piston 52 through a port 6|. The normal position of piston 52 is shown in Fig. 1. It is intended that the piston shall be operated hydraulically in either direction. However, in case of failure of oil pressure, a spring 52a returns the piston 52 to its normal position.

The valve 51 is positioned by means responsive to the movement of the lever 48 and to pressure in the intake manifold 85. For this purpose, the valve 51 is connected by a flexible rod 88, a clevis 88 and a pin 65 with a lever 56 pivoted on a pin 51, supported by a bridge 58 (Fig. 2) which connects the free ends of metal bellows 58 and 18. Bellows 68 is evacuated. Bellows 18 is connected by pipe 18:: to the intake manifold 85. As pressure in the intake manifold increases, bellows 18 will expand thereby causing pin 61 to move toward the left and when the intake manifold pressure decreases, the pin 61 will move toward the right. The valve 51 is positioned also by a cam II against which the upper end of the lever 65 is urged by a spring 12. The function of cam II is to select the pressure to be maintained in the manifold 85. Cam H is operated by the control lever 88 which, when moved counterclockwise, will cause an arm 18, connected with shaft 88, to move counterclockwise thereby causing movement of a link 14 toward the left to effect counterclockwise movement of a lever 15 connected with a shaft 15 which carries the cam 1 I.

The cam H is shown in Figs. 1 and 2 in its normal or lowest pressure selecting position. Movement of lever 48 to the left causes the cam 1| to move counterclockwise into a higher pressure selecting position, thereby causing, through the action of spring 12, a counterclockwise movement of lever 55 and a movement of valve 51 toward the right, thereby causing pressure fluid to enter through the port 58 to the right side of piston 52. Thereupon piston 52 moves left to cause clockwise movement of differential lever 81, 48 and counterclockwise movement of throttle valve II to cause it to open in order to increase the fuel pressure in manifold 85. When the pressure in manifold 85 equals the pressure selected by cam 1|, the bellows 18 will have expanded to such an extent as to cause the valve 51 to move to a position to close both passages 88 and 8| whereupon movement of the piston 52 toward the left will cease.

As the airplane ascends, the throttle valve 8| moves gradually toward full open position in order to maintain the selected pressure. The required pressure is obtained up to critical altitude by the combined efl'ect of the engine driven supercharger and the auxiliary, exhaust-turbinedriven supercharger 28. When the engine Is idling, the exhaust turbine should operate to drive the supercharger 28 at such speed as to overcome restriction to flow of air to the supercharger 84. During flight when the engine is required to operate faster and at higher manifold pressure, the auxiliary supercharger is required to operate faster in order that the combined effect of both superchargers will be such as to maintain the selected pressure. As the engine operates faster, there is more power available in the exhaust gas flowing to the turbine 2| to drive it at higher speed. In order that the auxiliary supercharger 28 will give the correct amount of boost to air flow so that the required pressure will be obtained for the power at which the engine is operating, it is necessary to so control the position of the waste gate 25 that the exhaust turbine M will be supplied with the correct amount of power from the exhaust gas. This control of waste gate position is effected by the waste gate controller 88 to be described. In this way the auxiliary supercharger 28 assists the engine driven supercharger 34 making available a selected pressure required for a certain engine speed.

The coordination for pressure selection and governed speed of the engine is effected by a cam 11 which is operated by shaft 44. Cam 11 cooperates with a follower roller 18 carried by a lever 18 pivoted at 18a. Lever 18 is connected with the adjusting mechanism of a propeller pitch governor not shown. Obviously movement of control lever 48 to effect a pressure selection by moving cam II will concurrently effect an engine governed speed selection by moving cam 11.

When the waste gate 25 is wide open as shown in Fig. 1, the exhaust turbine 2i will operate at minimum speed for a given engine; and, when the waste gate 25 is fully closed, the exhaust turbine 2i will operate at maximum speed. It has been found that satisfactory coordination of the two superchargers is obtained when the waste gate 25 is brought into a position about mid-way between fully open and fully closed positions.

The control of the waste gate 25 is effected by waste gate controller 88 which includes an hydraulic servomotor comprising a cylinder 8i and a piston 82 connected by a rod 83, a pin 84, link 85, a bell-crank lever 85, a link 8541, and a lever 86b with the shaft 26 which supports the waste gate. The admission of pressure fluid to the cylinder 8| is controlled by a valve 81 which slides in a ported guide 88. When valve 81 is moved toward the right from its position shown in Fig. 1, it will connect a fluid pressure inlet port 88 with a port 88 connected with the right end of the cylinder II to cause the piston 82 to move left and the waste gate 25 to move toward closed position. When the valve 81 is moved toward the left from the position shown, the fluid pressure inlet port 88 will be connected with a passage 8i leading to the left end of the cylinder III, to cause the piston 82 to move right and the waste gate 25 to move toward open position. It is intended that the piston 82 shall be operated hydraulically in both directions; but, in case of failure of oil pressure, a spring 82 will return the piston 82 to the normal position, thereby locating the waste gate 25 in that position which effects the lowest speed of the exhaust turbine.

The valve 81 is positioned in part by a pressure selecting device coordinated with the throttle controller 58 and in part by means responsive to pressure in the pipe 21 at the outlet of the auxiliary supercharger 28. To accomplish this, the valve 81 is connected by flexible rod 88, a clevis 84 (Fig. 11), a pin 85 with a lever 88 pivoted at 81 on a bridge 88 connecting the movable ends of flexible metal bellows 88 and I88. Bellows 88 is evacuated and bellows I88 is connected with pipe I8I extending into the air passage 21 provided with a plurality of holes I8Ia which face in the direction of air flow as indicated by arrow 21a. It is therefore apparent that the bellows I88 is responsive to impact pressure at the outlet of supercharger 28.

This air pressure is the sum of the pressure of the air entering the scoop I0 and the pressure effected by the supercharger 20. As the pressure in bellows I00 increases, it will expand to cause the pin 91 to move toward the left, this movement being resisted by springs 09a and 99b within the bellows 99. As the pressure in bellows I00 decreases, the collapsing of bellows I00 is resisted by'spring I00a within bellows I". These springs 99a, 90b and NM are so constructed and calibrated that the relation between variations in pressure within the bellows I00 and movements of the pin 91 is substantially a linear relation. Bellows 59 and "of regulator 50 contains springs 59a, 59b, 1011 (Fig. 2) equivalent to those contained within the bellows 99 and I00.

It will be noted, that, with respect to the waste gate controller 80 and the throttle valve regulator 50, there is substantial similarity as to their servomotors, control valves and valve controlling bellows. In fact, many of the parts thereof may be duplicates.

In order that the position of'valve 81 may be controlled in accordance with a selected pressure to be maintained, there is provided a pressure selecting cam IIO integral with a shaft IIOa received by the central bore of a shaft III (Fig. to which a lever H2 is attached. Shaft III has slots IIIb (Fig. 153) for receiving the ends of a pin II I 0 attached to shaft ll0a, thereby providing a lost motion connection for a purpose to be described. A spring 00 (Fig. 15) connects the flange IIOb of shaft M with the flange IIIa of shaft III and urges cam IIO clockwise (Fig. 15) and cam shaft IIOa counterclockwise (Fig. 15B) so that the pin I0 is urged counterclockwise into the position shown. The cam IIO will follow shaft III as it isrotated for the purpose of rotating the cam IIO between the positions shown in Figs. 1 and 11. Under a certain condition, rotation of cam I I0 clock- 6 pressure selection. When a higher pressure is demanded by moving pilot's lever 40 (Fig. 1) left and through the mechanism described the cam I I0 is rotated counter-clockwise for example into the position shown in Fig. 11. Before the equilibrium position of valve 01 is established as shown in Fig. 11, levers I21 and 96 are caused to move counterclockwise and valve 01 to move right, thereby placing intake port 09 in communication with port 90, thereby causing piston 02 to move left and the waste gate 25 to move toward closed position to increase the pressure in bellows I00. When the pressure in bellows I00 exceeds the ressure selected by cam IIO, valve 01 moves left om the position shown in Fig. 1 to place port 09 1 communication with port 0i, so that the piston 02 moves right to effect movement of the waste gate 25 toward open position so that the pressure in bellows I00 dewise (Fig. 11) is arrested by a screw 255, while shaft III may continue to rotate in a clockwise direction or counterclockwise in Fig. 153. Cam IIO selects outlet pressures at pipe 21 which, when boosted by supercharger 34, will make available the pressures selected by cam II for various positions of control lever 40. The pressures selected by cam IIO are below those selected by cam 1| for flight operation. Lever H2 is connected by link II3 with a lever II4 connected with a shaft II5 which is pivotally supported by the frame I2I of the controller 80 which, as shown in Fig. 11, is attached by screws I22 to the frame I20 which provides the cylinder III and a housing for the bellows 99 and I00. Lever H4 is connected as shown in Fig. 1 by a link IIB with an arm II'I operated by the shaft 44.

Referring to Fig. 8, screws I23 attach the frame I2I to a mounting bracket I24 which provides a pocket I25 (Fig. 11) for receiving a spring I22 and a spring guide I26a. Spring I25 urges the lower end of a lever I2'I against cam IIO. Lever I2! is pivoted upon a pin I20, and its upper end is connected by a pin I29, a clevis I30, 8. flexible rod I3I, a clevis I32 and a pin I33 with the upper end of lever 95. The pressure selecting cam II 0 of the waste gate controller 00 is coordinated with the pressure selecting cam II of the throttle regulator 50. Both of these cams move together when the throttle control lever 40 is moved. In Fig. 1, the cam H0 is shown in creases. The valve 01 is in the equilibrium position shown in Fig. 11 when the pressure in pipe 21 at the outlet of supercharger 20 equals the pressure selected by cam IIO. When this occurs, the waste gate 25 is about mid-way between wide open and fully closed positions, piston 52 (Fig. 11) being in mid position. The cam III effects a control of the waste gate 25 jointly with the bellows I00 (responsive to auxiliary supercharger outlet pressure) and with bellows I50 (responsive to impact pressure) such that auxiliary supercharger outlet pressure bears a predetermined relation to the pressure maintained by the throttle regulator 50.

To prevent surging, or hunting, the controller 20 is provided with a follow-up mechanism.

Referring to Figs. 1, 8 and 11, the connector 0311,

attached to the outer end of piston rod 03 for carrying the pin 04, receives a pivoting portion I40 of a rod I connected by pin I42 with a lever I44. Portion I40 is retained in connector 02:: by a screw I40a (Fig. 9). The hub I44a (Fig. 8A) of lever I44 is attached to a shaft I45 by a taper pin I44b which is wedged against the shaft by tightening a nut I44d on the threaded end I440 of the pin. (Lever H2 is attached to shaft III in a similar manner.) Shaft I45 (Fig. 15), which is journalled in a bearing I48 of housing I20, eccentrically supports the shaft III of cam III. When piston 82 moves left, the followup mechanism causes the axis of shaft III to move clockwise (Fig. 11). This has the effect of decreasing the pressure selection just as though the cam IIO had been rotated clockwise. During the complete movement of the piston 02 from right to left to close the waste gate, the pressure selection which had been for example in the neighborhood of 30" Hg, absolute, would installation for which the disclosed turbo-control was developed, that the waste gate 25 stabilizes to approximately half-open position as selected pressure is obtained. During a demand for higher pressure, piston 82 moves left and the waste gate closes entirely. Simultaneously, the selected pressure from the cam IIO will be approximately 2" Hg less than at waste gate stable position. This droop of 2" Hg effects the start of the cycle of moving the waste gate toward its stabilized position before the actual pressure at the supercharger outlet is reached. Therefore the tendency to over-boost the pressure is its normal position corresponding to the lowest 7| counteracted by a concurrent movement of the 7 waste gate 25 toward stable position. The opposite action occurs when a lower pressure is selected.

The portion of droop between half-open and fully closed positions is used also to prevent overspeeding of the turbine 2| when the ducts between the supercharger 20 and the engine (supercharger 34) are punctured or severed. For that purpose the droop may be increased somewhat above the minimum required for stability only.

It is apparent from the foregoing that the follow-up mechanism provides stability of operation of the controller 80, and prevents overspeeding of the turbine 2| caused by duct failure or air leaks since the regulator 80 is responsive to total pressure at the outlet of the turbo-supercharger 20.

During ascent of the airplane, the turbine 2I becomes stable at a speed capable of producing the pressure which was selected at low altitude for the climb to a higher altitude. ascends with the same selected outlet pressure in pipe 21, the turbine speed increases. During this increase, the following conditions will occur if no means are provided to prevent it: (1) for a moderate pressure selection in pipe 21, surge will develop in the air duct; (2) for a high pressure selection in pipe 21, the speed at which the turbine can safely operate will be exceeded. The controller 80 provides means for avoiding these conditions by an altitude responsive means for modifying the pressure selected by cam H0.

The altitude responsive means for modifying the pressure selection set by cam IIO comprises an aneroid bellows I50 (Fig. 11) sealed between plates II and I52 and evacuated. Plate I5I is attached to bracket I24 by an integral stud I5Ia and nuts I5Ib. Plate I52 is cupped to provide a wall I53 which is engaged by a rod I54 urged against the wall I53 by a spring I55 confined by a washer I56 (fixed to rod I54 by a snap ring I54a) and an abutment member I51 which, for the present may be considered fixed. Rod I54 is guided by the member I51 and supports the pin I28. A spring I58 is located between plates I5I and I52 to oppose movement of plate wall I53 toward plate I5I when atmospheric pressure is increasing and to urge plate I52 away from plate I5I when atmospheric pressure is decreasing. For proper response of the aneroid bellows I50 to pressure altitude available at the intake of supercharger 20, it is located in a chamber I60 connected by a pipe I6I (Fig. 1) with the scoop I8. The chamber I50 is provided by a recess in bracket I24 closed by a plate I62 having a flange threaded into the recess wall as shown in Fig. 11. Plate I82 has a central opening surrounded by a flange I83 attached to a tube I64 along which the cupped-portion of bellows plate I52 may slide. As pressure altitude in chamber I60 decreases, spring I58 expands and its expansion is resisted by spring I55. Springs I55 and I58 are so related that when the required speed of the turbine is reached, the pin I28 will move right to effect a control of the waste gate operating servomotor to prevent excess speed.

Fig. 18 shows a schedule of relations between engine governed speed and manifold pressure and auxiliary blower pressure to meet the operating requirements of a certain engine. Curve A- B-C is the manifold pressure curve for various positions of the main control lever 48 of controller 50 (Fig. 1) when water injection is used; and A-E-C is the manifold pressure As the airplane pressure available in the manifold, the outlet pressures of the supercharger 20 are those represented by curve D-E-F when water injection is used, and by curve D-EF' without water injection. In order to obtain the required blower outlet pressures at various altitudes, the spring I55 (Fig. 11) which controls the aneroid I58 must be variably stressed according to line opqr-s-t--u. (with water injection) or -v (without water injection), in Fig. 18. This line shows, for various positions of main lever 43, the altitude pressures (scale at the lower right of Fig. 18) at which the aneroid I50 should begin to exercise control over waste gate controller 88. More specifically, this line shows the various altitude pressures which, when added to the pressure of spring I55, gives a summation of forces balancing the spring I58. Fig. 18 shows that when a manifold pressure of 25" Hg has been selected by movement of lever to the 25 position, the pressure at the outlet of blower 28 should be 18 Hg. In order that this pressure will not be exceeded as the altitude increases, the aneroid should begin to move the pin I28 (Fig. 11) toward the right at altitude pressure 12.75 Hg. For pressure selection 40" Hg, the blower outlet pressure should be 26.25" Hg and altitude pressure at which pin I28 is moved right from normal by the aneroid I50 is 11.45" Hg. When the pressure selection is Hg, the blower outlet pressure should be 29 Hg and the altitude pressure at which pin I28 moves right from normal is 9.06" Hg. Line q-r denotes a transition from line opq to point 1' corresponding to which the turbine 2I should begin to operate at rated maximum speed, meaning the speed at which it may safely operate for a long period. In order to limit the turbine speed to the rated maximum (24,000 R. P. M. for example) it is necessary that the autitude pressure, at which pin I28 begins to move right from normal, be increased from 0.06 Hg to 11.5" Hg as the pressure selection is raised from 45" Hg to 55" Hg. While the turbo-blower speed remains constant between the 45" and the 55" pressure selection, the blower outlet pressure increases because more air is passing through the blower due to wider opening of the throttle and because there is more turbine power available to move the air since exhaust gas pressure is increasing with engine power output which increases with increase of intake pressure and with increase of speed.

The 55" pressure selection is for take-off" and higher pressures are for emergency." Emergency pressures may reach 61.15" without water injection as represented by line B-C and turbo blower outlet pressure may reach 37.5 as represented by line E-F'. with water injection, the manifold pressure may reach 85" (Point C) and the turbo blower outlet pressure may reach 49" (Point F). In passing from 55" to 61.15" pressure selection the turbo outlet pressure passes from 34.5" to 37.5" and the pressure altitude at which pin I28 starts to move right from normal changes from 11.5" to 11.15" Hg. The result of this change of control by the aneroid I is to increase the speed of the turbine from the rated maximum 24,000 R. P. M. to 26,400 R. P. M. which is considered safe for emergency operation for relatively short periods. When water injection is used, the control of the aneroid spring I is that represented by line t-u extruding from 11.15" to 15" altitude pressure. When water incurve without water injection. To make this 1 jectionisnot usedamechanical stop (not shown) limits movement of the lever 40 to such position that lever 43 cannot move past the 70 position. when water injection is used, the stop is retracted and the emergency manifold pressure can have values on line 3-0, while the turbo blower outlet pressure attains corresponding values on the line E-F. when the supply of water ceases, means are provided for automatically reducing the manifold pressure from a value on line 3-0 to the maximum represented by line B--C' and the turbo blower outlet pressure from a value on line E-F to the maximum represented by line E-F". These means include devices to be described later for automatically pushing lever 88'away from cam H of regulator 50 and for automatically pushing the cam N of controller 80 to a position of lower pressure selection and for automatically maintaining the spring I55 under the same compression that it must have in order to meet the condition denoted by point t (11.15") in Fig. 18. The effect on the controller 80 is the same as though line t-u were moved into coincidence with line t-v.

In order to meet the conditions denoted by line op--qrstu, there is provided a lever I10 pivoted on a pin "I and providing a cam slot I12 having a configuration for effecting the control represented by this line. Slot I12 receives a pin I13 on a lever I14 attached to shaft I I which is operated by lever I I4, which is operated by main control lever 40. Therefore the movements of lever I are coordinated with pressure selection. Lever I10 is urged left by a spring I15 which maintains the right edge of the slot I12 against the pin I13. Lever I10 engages member I51 which as shown in Fig. 150 has a notch between two flanges I51a and "1b between which the lever I10 is located, the notch defining surface I51c being engaged by the lever I10. As lever 40 is moved to select various pressures, the lever I10 is moved into various positions by pin I13 in order to variably stress the spring I55 in order to obtain the control represented by line o-p q--rstu.

The pivot pin "I is adjustable laterally by moving a block I80 on which it is mounted. The block I80 slides in a recess I8I provided by housing I 2I and closed by bracket I24; and a spring I82 urges the block right in Fig. 11 or up in Fig. 14 to cause one side of its tapered hole I83 to engage the tapered end of a screw I84 which is threaded into a boss I85 of housing I2I. The screw I84 is turned by a screw driver applied to notches I86 (one shown in Fig. 13) in the left end of the screw in order to move the block I80 endwise; and the screw I84 is locked in adjusted position by a self-locking nut' I81 which becomes accessible upon removal of a guard I88 attached to screw I84 by a screw I88. The screw I84 has a slot I90 for receiving a key I9I integral with a washer I92 having a pointer I83 moving past graduations on a dial I84 (Fig. 8), the hub of which can be secured by a screw I85 to the boss I85 in the desired location. An adjustment of screw I84 is made to obtain the effect represented by a normal requirement such as denoted by the line op-qrst-u and the screw I84 is locked by the nut I81. The dial I94 is moved so that its zero mark is adjacent the pointer I93 and the dial is fixed to boss I85 by tightening the screw I95. The dial graduations will thereafter be used to indicate the extent of modification of the normal setting of the lever I10 when the screw I84 is thereafter turned in either direction to effect such modification. The

modification which can be effected by timing the screw I84 in either direction is that which would be denoted by rotating the line -4-444- t-o as a wliole about the point o in either direction. If this line is raised the manifold pressure would be raised. and vice versa. Obviouslythislineshouldbeashighaspossible while avoiding detonation.

An initial adjustment of the bellows and I00 and pin 81 (Fig. 11) may be required. To do this, a screw 200 (Fig. 12) threaded into a screw 202 is removed to obtain removal of a guard "I. A self-locking nut 204 is loosened to permit turning the screw 202 by applying a screw driver to its slots 203 (one shown in Fig. 12). When screw 202 is turned an eccentric pin 208 turns to push on a screw head 208 having a slot 201 which receives the pin 205. Head 208 has a threaded shank 203 screwed into the left end plate of bellows 38. In this way the turning of screw 202 eifects a longitudinal adjustment of the bellows and I00 and a lateral adjustment of the pin A similar adjustment for bellows 88 and 10 and pin 81 of throttle regulator 50 is provided as shown in Fig. 2. To make this adjustment a screw 2I0, passing through a screw 2I I (threaded into the cover plate P of housing H), is removed to obtain removal of a guard 2I2, so that a self-locking nut 2I3 may be loosened. Screw 2 is turned by applying a screw driver to its notches 2 (one shown in Fig. 2). As the screw 2 i turned the central boss 2I5 bears against the right end of the screw under the action of the bellows springs, and the bellows are longitudinally adjusted and the pin 81 is laterally adjusted.

The cam H is so designed as to effect the selection of pressures up to Kg. It is operative to perform the function indicated by line 3-0 (Fig. 18) when water injection is being used, otherwise its function is limited to selection of pressures up to 61.15" as denoted by line B-C. The control of the function of cam H in response to pressure or absence of water injection is effected by fluid pressure responsive means for controlling the position of a stop rod 220 which normally is maintained in the position for limiting pressure selection to 61.15" (or whatever is safe for engine operation without water injection) by a spring 22l acting through a rod 222 guided by a bushing 223, a pin 222a carried by the rod 222, a lever 224 fixed to a shaft 225 and having an upper forked end receiving the pin 222a, a pin 228 received by the lower forked end of the lever 224, and carried by a lever 221 pivoted at 228 and having an arm bearing against a disc 228 fixed to the rod 220, and urged by a spring 230 against the lever 221. Movement of the rod 222 to the right under the action of spring 22I is limited by a stop screw 23I threaded through a diaphragm cover C and retained by a self-locking nut 232. Cover C and a diaphragm 233 (located between discs 234 attached by self-locking nut 234a to the threaded right end of rod 222) define a pressure fluid receiving chamber 235 connected by a passage 238 with a pipetapped opening 231 for the attachment of a pipe 308 (Fig. 1) connected with the water injection system to be described by a device which cause chamber 235 to be connected with the water pressure source so long as water flows out the injection nozzle. When the water flows out of the injection nozzle, water pressure builds up in the chamber 235 and spring 22I is overcome ll and the diaphragm 233 moves left and the rod 228 moves left away from the lever 88 so that it may follow the cam 1| into the surface portions thereof nearest the cam axis whereby high pressures are selected when required. When water injection ceases, fluid pressure in chamber 235 falls and spring 22l becomes operative to return the rod 228 into the path of movement of the lever 53 to prevent it from following the cam 1I when in certain positions of high pressure selection.

The waste gate controller 38 has a similar device. A pipe 381 (Fig. 1) conducts a pressure fluid to a tapped opening 248 (Fig. '1) in bracket I24, said opening being connected by passage 24I with a chamber 242 defined by diaphragm 243 and a cover 244. Diaphragm 243 is confined between plates 245 attached to a rod 246 by a selflocking nut 241 threaded on the rod. The rod 243 is urged left (Fig. 6) and down (Fig. '1) by a spring 248; and this movement is limited by the engagement of the rod 245 with a stop screw 243 threaded through the cover 244 and retained by a self-locking nut 258. Rod 246 slides in a bushing I supported by the bracket I24 and is attached to a member 252 providing a stop arm 253 for engaging the member I51 (Figs. 15, 15A, 150) which confines the spring I55. As shown in Fig. 150 arm 253 is received between flanges I51d and I51e of part I51 and will bear against the surface I51f, when there is no water injection and when the pressure selection is 61.15 and the turbo blower outlet pressure is 37.5. The member 252 has an arm 254 (Fig. 6) which carries a screw 255. When there is no water injection, screw 255 blocks movement of cam I'I8 beyond the position for 37 turbo blower outlet pressure (Fig. 18). At the same time, the arm 253 keeps the spring I55 under that state of compression required for 11.15" altitude pressures as indicated by line tv so that turbine speed will not exceed 26,400 r. p. in. When the main control lever 48 of controller 58 is moved further than the 70 position in anticipation of the use of water injection, spring II8c (Fig. 15) is additionally twisted while shaft III moves counterclockwise (Fig. 158) relative to pin Mic. The droop control, effected by movement of piston 82, rod 83, link I, lever I44 and shaft I45, remains effective because cam H8 and lever I21 are always engaged.

When water injection is operating, pressure fluid acts concurrently against diaphragm 233 (Fig. 2) of regulator 58 and diaphragm 243 (Fig.

8) of controller 88 whereupon rod 228 moves out I.

of the path of movement of lever 66 (Fig. 2) to permit it to follow cam 1| in its pressure selecting position exceeding 61.15" and whereupon screw 255 moves to the right of cam H8 to allow it to move (under action of spring II8c (Fig. 15)) into pressure selecting positions exceeding 37.5", and whereupon arm 253 moves out of the path of movement of member I51 to allow spring I55 to move member I51 against the lever I18. Then the control functions according to lines 13-42, E-F and tu of Fig. 18.

Concurrently with the movement of diaphragm 233 under fluid pressure, a valve 288 (Fig. 1) which is normally closed is moved to 233a to open a by-pass between pipes 21 and 28 so that the intercooler is by-passed. For this purpose, the valve 268 (Fig. 1) is operated by a servo motor having a cylinder 28I receiving a piston 282 attached to a rod 253 connected with a lever 254 attached to a shaft 255 carrying the valve 238. The cylinder receives pressure fluid through passages 288 or 281 controlled by a valve 288 which controls the admission of pressure fluid entering a pipe 283. Valve 258 is connected by link 218, lever 21I (pivoted at 212) with lever 213 (through a pin 214) attached to shaft 225. These parts are so constructed and arranged that movement of diaphragm 233 to the left (under fluid pressure) causes valve 288 to move down so that the lower end of cylinder 28I receives pressure fluid while the upper end discharges and piston 282 moves up and valve 288 moves to 268a. When the intercooler bypass is used a certain loss of pressure in the intercooler is avoided and turbo blower outlet pressure need not be carried to 49" to obtain manifold pressure. If, for example, the loss in the intercooler is 8", the maximum turboblower outlet pressure will be 41" as indicated at N in Fig. 22. When the system includes the intercooler by-pass, the control cams are shaped so as to obtain the control shown in Fig. 2-2, in which G--IK is the manifold pressure line, LMN is the blower outlet pressure line and line o'p'-q-r's'-t'--u' represents the control by cam I12 when water injection is operating. Without water. injection the system will function according to IH-H-', M-N' and t-v' when the cam 1| is located for the selection of pressures exceeding 61.15".

The BC portion of the manifold pressure line (Fig. 18) is greater in slope than the connecting lower portion of this line. To obtain this effect, a spring 288 (Fig. 2) is placed in bellows 18 of regulator 58. Spring 288 is located in a fixed cup MI and is engaged by a self-locking nut 282 on a rod 283 fixed to the left end plate of bellows 18. The nut 282 does not compress spring 288 until the pressure selection exceeds 61.15 whereupon the characteristic of the spring combination so changes as to produce the effect denoted by BC (Fig. 18).

When the system is provided with the intercooler by-pass, the nut 282 is so adjusted as to begin to compress the spring 283 at the 55 pressure selecting position of lever 43 (at its 72.5" position, Fig. 22). Therefore the increase in slope of the manifold pressure line begins at I. Manifold pressures follow I-K when water injection is operating and the intercooler by-pass is opened. When water injection ceases and the intercooler by-pass closes concurrently therewith, the actual manifold pressure immediately falls from JK to H-H when the lever 43 is above the 61.15" pressure selecting position, and the actual manifold pressure immediately falls from I--J to I-H when the lever 43 is in a pressure selecting position between 55" and 61.15".

In Fig. 1 there is a diagram of the water injection system. The water or water-alcohol mixture is contained in a tank 388 connected by a pipe 38I with a motor driven pump 382 which forces the water through a metering device 383 and a pipe 384 to a nozzle 385 through which liquid fuel flows from the carburetor 38. So long as the water fiows out the nozzle 385 at the required rate, water under pressure will be conducted by the pipes 386 and 381 to the diaphragm chambers of regulator 58 and controller 88. When water ceases to flow at the required rate from the nozzle 385, the diaphragm chambers are not supplied with water under pressure to overcome the springs which oppose movement of the diaphragm and effect, through the 13 stop members, the limitation of manifold pressures to a value safe for engine operation without water injection. A water injection system with which the apparatus of the present application can..be used is described and claimed in the patent to Dolza, et al., No. 2,491,484, granted December 20, 1949.

When cruising at 45" pressure selection, for example, as in formation flight, the selected pressure obtained by the turbo control cam H exceeds the pressure required to produce the pressure selected by the throttle regulator cam H by an amount called positive overlap. This overlap provides immediate response to throttle opening and the acceleration necessary when changing from formation flight tomilitary. If overlap in summer is 2", for example, it will be 4" in winter on account of the difference in air density. For military power at 55" pressure se lection, for example, the positive overlap is zero in summer and 2 /2" in winter. In the emergency pressure range, such as 61.5" pressure selection, the overlap should be negative in order to obtain approximate borderline detonation control of pressure. Negative overlap means that the selected pressure obtained by cam H0 the surge range if the turbine speed is in excess I of the amount of air being pulled through it by operation of the engine driven supercharger. To get out of the surge range, it is necessary to boost the air flow or reduce the turboblower speed.

Fig. 19 shows the relation of turboblower outlet pressure (b.o.p.) and Q which is the quantity of air delivered from turboblower. The abscissa, left to right, shows increasing Q. The ordinate shows corresponding values of b.o.p. Assuming a constant altitude, Curve I is for the blower speed N1 less than N2 and less than N3; Curve II is for blower speed N2 greater than N1 and less than N; and Curve III is for blower speed N3 greater than N2 and N1.

The steep part of each curve is the surge range. N1 being a constant for curve I, as Q increases from zero, b.o.p. increases according to curve I, rapidly from a to b, (surge range), and decreases gradually through the stable range b to :L'. For a higher speed N2, Q must be raised to such value that Q equals c before the stable range is reached. For a still higher speed, N3, Q must be raised to such value that Q equals 0 before the stable range is reached.

Therefore it is apparent that avoidance of the surge range is avoided by increasing Q or by reducing N.

Fig. 18 shows that, when altitude pressure is 11.45" (q), the aneroid has so controlled the b.o.p. selection as to give 26.25" b.o.p. when the main control member has been moved to select 40" and engine speed 2430 R. P. M. Surge is avoided because the engine driven supercharger is driven at such speed coordinated with engine speed 2430 R. P. M. as to cause such air flow from the turboblower that Q/N is in the stable range. Point q on Fig. 18 denotes that, when altitude corresponding to 11.45" pressure is reached, the turbine is operating at maximum safe speed in order to give 26.25" b.o.p. which combined with the engine blower gives 40" manifold pressure. If the pilot selects a lower manifold pressure at altitude pressure 11.45", he may flnd that the pressure actually existing in intake will be so much less than the selected pressure that he will not be able to cruise and he must move the control lever to a higher pressure selecting position in order to maintain minimum cruise pressure in the intake. By such movement of the control lever, the engine speed is raised with the result that Q/N is raised to value in the stable operating range of the turboblower.

For selections up to 40" manifold pressure. the aneroid expands with increasing altitude against the spring I" in order to keep the turbine speed within the limit of 24,000 R. P. M. For higher pressure selections, the compression of spring I" is modified by shifting lever I10 according to rst-u. (t-u provided water injectionisused. otherwise t-v). The higher pressure selections do not run into surge; but the lower pressure selections may run into that condition. Avoidance of surge is obtained by the aneroid control of turbospeed in the manner represented by line o-p-q (Fig. 18). a

Line A-B of Fig. 20 represents cruising at 25,000 feet using pressure selections 55" down to 25", According to Fig. 18, the turbo blower operates at maximum rated speed at 55" pressure selections (control on line rs). From 40" to 25" pressure selection, the aneroid obeys lines opq so that turbospeed does not exceed the maximum. As the pressure selection is reduced, exhaust pressure .decreases, and turbospeed decreases. Therefore Q and N (of Q/N) are reduced in about the same proportion so that the Q/N value as related to b.o.p. value is not in the surge range of the curve of Q related to b.o.p.

For example, at 25,000 altitude the selected pressure can be reduced to 25" for minimum cruise without running into Q/N surge. At 35,000 altitude, when 55" is called for, only 41" can be obtained, because the turbospeed is limited. Therefore C on line CE-D representing cruising at 35,000 ft. is lower than A. As the pressure called for is reduced from 55" to 35", the pressure obtained is 41" to 25". Since the plane cannot maintain the elevation of 35,000 it, when the actual intake pressure falls below 25", movement of the control lever to the 25" selecting position would cause the descent from 35,000 ft. to 25,000 ft. as represented by E-B- While thus descending the turbospeed would decrease because it would not be required to run as fast at 25,000 as at 35,000 in order to maintain the 25 called for. In order to maintain 35,000, the pilot must move the control lever to about 35" pressure selecting position to actually get 25". In doing so the engine speed is raised to 2200 R. P. M. so that Q (quantity of air flowing out of turbo blower) increases to keep Q/N in the stable range.

Therefore it is apparent that the aneroid by following the op-q line eifects such control of the turbospeed regulator that it is equivalent to reducing the pressure selection of the turbospeed regulator. The pressure called for can be obtained only so long as the maximum speed of the turbo is not exceeded. When the altitude is high (35,000 for example) the pressure obtained is less than the pressure selected by the pilot. Therefore he cannot maintain flight by moving the control lever to a position of minimum cruise. The lever can be moved only so far back toward idle position that the corresponding actual pressure is minimum cruise pressure. At this setting of the control lever, the engine speed is high enough to prevent Q/N surge.

In Fig. 20, Fr-D represents a gentle glide from 35,000 to 25,000. The control lever is gradually moved from the 35 to the 25" pressure selecting position. As the altitude decreases the aneroid contracts and effects a control of the turbospeed regulator which is equivalent to raising the selection of blower outlet pressure (b.o.p.). At the same time, less and less b.o.p. is demanded as the control lever approaches the 25" position therefore the turbo blower speed decreases. The N of Q/N decreases. Also while the control lever is approaching the 25" position, the engine speed is decreasing, therefore Q of Q/N decreases. But Q/N remains in the range of stable operation of the turboblower during the glide from 35,000 to 25,000.

In the lower range of pressure selections, surge is avoided by maintaining sufilciently high value of Q at high altitude and low pressure selection. When descending at a lower altitude with a low pressure selection, Q decreases about in the same proportion as N, and Q/N remains about the same.

In the higher range of pressure selections with higher engine speeds corresponding thereto, Q is large and N is limited by the maximum speed setting. Therefore Q/N is much greater than in the case of low pressure selections and is even further removed from the surge range.

Fig. 23 shows the relations between turboblower outlet pressure (b.o.p.) and altitude and turbospeed. Line I is the 24,000 R. P. M. line for guaranteed maximum for continuous operation. Line II is the 26,400 R. P. M. line for overspeed allowable for emergency. Line III is'a 28,000 R. P. M. line which would be allowable for emergeney if improved materials become available for strengthening the turbine. Points A1, A2, A: (which correspond respectively to points a1, an, an on the 29" pressure line) show the critical altitudes when the b.o.p. is 29" which corresponds to 45" manifold pressure (Fig. 18) which is in the cruising range. Points B1, B2, B3 (corresponding to the points b1, b2, b: on the 34.5" pressure line) show the critical altitudes when the b.o.p. is 34.5" which corresponds to 55" manifold pressure (Fig. 18) which is military pressure. Points Cl, C2, C3 (corresponding to points c1, 02, ca, on the 37.5" pressure line) show the critical altitudes when b.o.p. is 37.5" which corresponds to 61.15" manifold pressure (Fig. 18) which is in the emergency range and is the allowable maximum without water injection. Points D1, D2, D3 (corresponding to points d1, d2, d: on the 49" pressure line) show the critical altitudes when b.o.p. is 49" which corresponds to 85" manifold pressure which is the allowable maximum with water injection.

Fig. 24 gives a resum of the functions of cam I12 which have been described in detail heretofore.

In order to obtain more accurate turbospeed control under all conditions including leaks in the duct leading from the turboblower to the carburetor it is advisable to make the controller III subject to control by turboblower outlet pressure rather than carburetor upper deck pressure. The reasons for this will be explained with reference to Fig. 21 in which the abscissa represents weight of air through the turboblower at constant engine speed and the ordinates of the upper part of the figure represent horse-power and the ordinates of the lower part represent turboblower outlet pressure.

If the waste gate is closed and all the air from the blower is fed to the engine and, in return,

all the resultant exhaust goes through the turbine, the power that can be generated by the exhaust turbine is represented by line A2--Bz. The power absorbed by the blower is represented by line A1B1. The area (shaded by vertical lines) between these lines is power available for acceleration; and this power is wasted through the waste gate at fixed operating conditions.

When air leak in duct 21 is introduced, line Bl-cl denotes the increase of power absorbed by the turboblower. Line B4-C4 shows that the carburetor upper deck pressure has decreased, thereby indicating less air flowing to the engine and consequently less exhaust available to the turbine. Bz-Cr denotes that the available power from the exhaust has been reduced as leakage increases from B to C until, at C1, it is equal to the power required by the blower. The waste gate is consequently closed. C1D1 denotes that the turbine speed decreases due to decrease in exhaust energy. Ba-Ca denotes decrease of turboblower outlet pressure.

The turbo control is so designed that, when the pressure is reduced from the selected value, the

waste gate closes until the selected pressure is restored; but, since the follow-up mechanism (link I (Fig. 8), lever I44, shaft I45 eccentrically supporting shaft Ill) causes a droop or reduction in the pressure selected by cam H0 approximately equal to the difference between B: and C3, the turbine speed will not increase because B3 minus C3 is the turboblower total outlet pressure change at fixed engine speed.

C4 is not a fixed value but depends on the location of the leak. C4 is lower when the leakage is next to the blower than when the leakage is next to the carburetor. However B4 minus C4 is considerably greater than B: minus Ca; therefore more droop in turboblower selected pressure would be required to prevent overspeeding of the turbine if the turbospeed control were subjected to control by carburetor upper deck pressure than when subject to control by turboblower outlet pressure. Therefore it is advanageous to connect the pipe i0l (Fig. l) with the outlet of the turboblower.

The oil pressure line comprises inlet pipe 3l0 (Fig. 1), arrow 3 indicating pressure oil, pipe 3| 4 connected with port 39 of controller 30, pipe 3|! connected with pipes M3 and 269. Pipe 3" is connected with port 59 of regulator 50. The discharge of oil from the cylinder 5| of regulator 50 (Fig. 2) fills the bellows chamber 330 to the level of line 33! (Fig. 3) and overflows into passage 332 (Fig. 3) connected with drain not shown. When the regulator 50 is not operating, oil drains slowly from the bottom of chamber 333 into the pocket 333 (Fig. 2) and through a restricted passage 334 into the drain.

The discharge of oil from the cylinder 31 of controller flows to the bellows chamber 343 (Figs. 11 and 17) either directly out of the valve guide 33 or through passages 88b and 880. This discharge fills chamber 340 to about the level of rod I3I (Fig. 11) and it flows down into the housing I (Fig. 15) and out through a hole 342 covered by a plate 343 to which a drain pipe 344 is attached. When the controller 80 is not operating the oil in the bellows chamber 340 (Fig. 11) drains slowly through a restricted passage I into housing l2l.

As shown diagrammatically in Fig. l, pipe 10.1: connects intake manifold 35 with bellows 10. As shown in Fig. 3, pipe 10:: is connected with passages 32l, 322 and 323. As shown in Fig. 2,

17 the left end or member 28! clears the rod 2" so that passage 323 is in connection with the interior of bellows 10.

While the embodiment of the present invention as herein disclosed, constitutes a preierred'torm, it is to be understood that other forms might be adopted, all coming within the scope oi the claims which follow.

What is claimed is as follows:

1. Apparatus for controlling the intake pressure of an internal combustion engine supercharged by an engine driven blower and an auxiliary blower operated by an engine exhaust turbine comprising, in combination, a throttle valve for adjusting intake pressures, a turbine waste gate for adjusting turbine speed, a member for adjusting engine governed speed, a throttle valve regulator having a device for selecting an intake pressure to be maintainrd and a device responsive to intake pressure and a throttle valve operating servo motor under control by said devices of the throttle valve regulator for adjusting the throttle valve to correct for deviations of actual intake pressure from selected intake pressure, a waste gate regulator having a device for selecting an auxiliary blower outlet pressure to be maintained and a device responsive to auxiliary blower outlet pressure and a waste gate operating servo motor under control by said devices of the waste gate regulator for adjusting the waste gate to correct for deviations of actual auxiliary blower outlet pressure from the selected auxiliary outlet pressure, an altitude pressure responsive instrument for modifying the selected auxiliary blower outlet pressure in order to limit the turbine speed, a mechanism for determining at what altitude pressure said instrument shall become effective, and manually operable means for effecting, in coordination according to a predetermined schedule, an adjustment of the engine speed control member, an adjustment of the device for selecting an intake pressure, an adjustment of the device for selecting a blower outlet pressure and an adjustment of said mechanism.

2. Apparatus according to claim 1 further characterized by the fact that said mechanism includes a manually actuated cam which is adjusted in coordination with the selection of pressures in the cruising range so that the turbine speed is limited to values less than maximum rated value and, in coordination with the selection of pressures above the cruising range, so that the turbine speed attains the maximum rated value.

3. Apparatus according to claim 1 further characterized by the fact that said mechanism includes a manually actuated cam which is adjusted in coordination with the selection of pressures in the cruising range so that the turbine speed is limited to values less than maximum rated value and, in coordination with the selection of pressures for operation of the engine at normal maximum power, so that the turbine speed will be limited to a maximum rated value and, in coordination with the selection of pressures for emergency operation of the engine, so that the turbine speed will be limited to a certain value above maximum rated value.

4. Apparatus according to claim 1 further characterized by the provision of means normally operative to limit the control by said regulators to the attainment of intake pressures safe for engine operation without detonation, and fluid pressure responsive means for rendering said limiting means inoperative.

5. Apparatus according to claim 1 further characterized by the provision oi means responsive to the operation 01' the second servo-motor to move the waste-gate toward closed position for effecting a reduction in auxiliary blower outlet pressure selection.

6. Apparatus for controlling the intake pressure of an internal combustion engine supercharged by an engine driven blower and an auxiliary blower operated by an engine exhaust turbine comprising, in combination, a throttle valve for adjusting intake pressure, a turbine waste gate for adjusting turbine speed, a member for adjusting engine governed speed, a throttle valve regulator having a rotary datum cam for selecting an intake pressure to be maintained and a bellows responsive to intake pressure and a throttle valve operating servomotor under control by said cam and bellows for adjusting the throttle valve to correct for deviations of actual intake pressure from selected intake pressure, a waste gate regulator having a rotary datum cam for selecting an auxiliary blower outlet pressure to be maintained and a bellows responsive to auxiliary blower outlet pressure and a waste gate operating servomotor under control by the cam and bellows of the waste gate regulator for adjusting the waste gate to correct for deviations of the actual auxiliary blower outlet pressure from the selected auxiliary blower outlet pressure, an altitude pressure responsive bellows for modifying the auxiliary blower outlet pressure selection in order to limit the turbine speed, a spring opposing expansion of the last named bellows; means for variably stressing said spring in order to determine at what altitude pressure said last named bellows shall become effective, and manually operable means for effecting, in coordination according to a predetermined schedule, an adjustment of the engine speed control member, adjustments or the datum cams or the regulators and an adjustment of said spring stressing means.

7; Apparatus according to claim 6 further characterized by the fact that the means for variably stressing the spring includes a spring abutment member and a manually actuated abutment member positioning cam having a contour such that, when said cam is adjusted in coordination with the selections of pressures in the cruising range, the turbine speed is limited to values less than maximum rated value and such that, when said cam is adjusted in coordination with the selection of pressures above the cruising range, the turbine speed attains the maximum rated value.

8. Apparatus according to claim 6 ifurther characterized by the fact that the meansior variably stressing the spring includes a spring abutment member and a manually actuated abutment member positioning cam having a contour such that, when said cam is adjusted in coordination with the selection or pressures in the cruising range, the turbine speed is limited to values less than maximum rated value and such that, when said cam is adjusted in coordination with the selection of pressures for operation of the engine at normal maximum power, the turbine speed will be limited to a maximum rated value and such that, when said cam is adjusted in coordination with the selection of pressures for emergency operation of the engine, the turbine speed will be limited to a certain value above maximum rated value.

9. Apparatus according to claim 6 further characterised by the provision of means for arresting movement the cam followers 0! the datum cams oi the regulators when the manually operable means is moved into positions for obtaining a certain high value range otpressure selections whereby the intake pressure is limited to a value safe for engine operation without detonation, and means for rendering inoperative said cam follower arresting means.

10. Apparatus according to claim 6 further characterized by the provision of means responsive to the operation of the second servo-motor to move the waste-gate toward closed position and for eiiecting such movement of the datum cam of the waste-gate regulator as to elect a reduction in auxiliary blower outlet pressure selection.

11. In apparatus for controlling the intake pressure of an internal combustion engine supercharged by a main blower and by a variable speed auxiliary blower and having a throttle valve for controlling intake pressure, the combination comprising a regulator for positioning the throttle valve so as to maintain a selected intake pressure, means for selecting the intake pressure to be maintained, an auxiliary blower speed controller for causing the auxiliary blower to operate at a speed that will produce a selected blower outlet pressure, means for selecting the blower outlet pressure to be maintained, and a manually operable means for adjusting both said pressure selecting means.

12. In apparatus for controlling the intake pressure of an internal combustion engine supercharged by a main blower and by a variable speed auxiliary blower and having a throttle valve for controlling intake pressure, the combination comprising a regulator for positioning the throttle valve so as to maintain a selected intake pressure, means for selecting the intake pressure to be maintained, an auxiliary blower speed controller for causing the auxiliary blower to operate at a speed that will produce a selected blower outlet pressure, means for selecting the blower outlet pressure to be maintained, a manually operable means for adjusting both said pressure selecting means, and means for moditying the auxiliary hlower-outlet-pressure selection without changing the setting of said manually operable means.

13. In apparatus for controlling the intake pressure of an internal combustion engine supercharged by a main blower and by a variable speed auxiliary blower and having a throttle valve for controlling intake pressure, the combination comprising a regulator for positioning the throttle valve so as to maintain a selected intake pressure, means for selecting the intake pressure to be maintained, an auxiliary blower speed controller for causing the auxiliary blower to operate at a speed that will produce a selected bloweroutlet-pressure, means for selecting the blower- 20 to be maintained, an auxiliary blower speed controller for causing the auxiliary blower to operate at a speed that will produce a selected bloweroutlet-pressure, means for selecting the bloweroutlet-pressure to be maintained, manually operable means tor adjusting both said pressure selecting means, altitude pressure responsive means for modifying the auxiliary-blower-outlet-pressure selection without changing the setting 0! said manually operable means, and manually operable means coordinated with the manual adjustment or both said pressure selecting means for varying the altitude-pressure at which the blower outlet pressure selection modifying means becomes eifective.

15. In apparatus for controlling the intake pressure of an internal combustion engine supercharged by a main blower and by a variable speed auxiliary blower and having a throttle valve for controlling intake pressure, the combination comprising a regulator for positioning the throttle valve so as to maintain a selected intake pressure, means for selecting the intake pressure to be maintained, an auxiliary blower speed controller for causing the auxiliary blower to operate at a speed that will produce a selected blower-outlet-pressure to be maintained, manually operable means (or adjusting both said pressure selecting means, and means actuated in response to operation of the auxiliary-blower-speed controller to increase speed for decreasing the auxiliary-blower-outlet-pressure selection.

16. In combination with an internal combustion engine having a variable speed supercharger, means for maintaining selected pressures in the engine intake pipe and means for selecting a particular pressure to be maintained, means for controlling the speed of the supercharger comprising a speed controlling element, a servo-motor for operating said element, a member (or controlling the operation of the servo-motor, mechanism for operating said member including a bellows responsive to the supercharger outlet pressure and a cam for selecting said outlet pressure and means for concurrently operating said cam and the means for selecting the engine intake pressure.

17. For use with a variable speed blower for an internal combustion engine, a blower speed controller comprising a servo-motor for operating a speed varying element, a member for controlling the servo-motor, and apparatus for eilecting a joint control of said member and including a manually positioned blower-outlet-pressureselecting cam, a bellows responsive to bloweroutlet-pressure, and means responsive to operation of the servo-motor for shifting the cam.

18. In combination with an internal combustion engine having a variable speed supercharger. means for maintaining selected pressures in the engine intake pipe and means for selecting a particular pressure to be maintained. means for controlling the speed of the supercharger comprising a speed controlling element, a servo-motor for operating said element, a member for controlling the operation of the servo-motor, mechanism for operating said member including a bellows responsive to the supercharger outlet pressure. a cam for selecting said outlet pressure and means for concurrently operating said cam and the means for selecting the engine intake pressure and a bellows responsive to altitude pressure for also controlling the action 01' the member which regulates the action of the servo-motor.

19. For use with a variable speed blower for an 

